This thesis investigates the coexistence of heterogeneous cognitive radio systems, with directional user antennas. The coexistence scenarios of High Altitude Platform-Terrestrial systems and multiple terrestrial systems are examined. Spectrum etiquettes and the game theoretical assignment techniques are applied to improve the coexistence performance. Two spectrum etiquettes called CINR and INR based, for use on the downlink of coexisting systems have been developed. The Interaction Probability has been developed to quantify the interaction level. The mitigating interaction techniques have also been discussed. The use of game theory with novel multivariable payoff functions has been applied to formulate the non-cooperative multistage spectrum sharing games as an alternative assignment technique. Path Gain Ratio (PGR) is used as a parameter to determine the cost/benefits of specific transmit power levels. Payoff functions have been shown as a way to control the users’ behaviour and to represent the requirements of the related parties such as the systems, users, and regulator(s). Coexistence without any power control is feasible with the help of user directional antennas and operating with low rate modulation. Although both spectrum etiquettes enhance the performance, the spectrum sharing games outperform them. The spectrum sharing games reach the Nash Equilibrium (NE) with a high percentage depending on the number of players in a game and the interference level but it is shown that users not reaching the Nash Equilibrium still have adequate performance.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:488738 |
| Date | January 2008 |
| Creators | Likitthanasate, Pairoj |
| Publisher | University of York |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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